"It was a traveling, quite expedient, little light. It was bright blue, leaving a trail of light particles," Leona Henry, an officer at Lewis Prison in Buckeye, told The Republic.

Henry ruled out Northern Lights since Arizona is too far south, then wondered if it was a missile from North Korea.

"It left this gorgeous blue trail across the entire sky," she said. "It just lit up the sky."

Leona Henry took this photo of the assumed rocket at her job at Lewis Prison in Buckeye.(Photo: Leona Henry/Special for The Republic)

SpaceX tweeted around 4:30 p.m. that its launch from Vandenberg Air Force Base north of Santa Barbara would occur in about an hour.

The Iridium-4 is the fourth set of 10 satellites in a series of 75 total satellites that SpaceX will launch for its global satellite constellation, the company said on its website. A SpaceX spokesman did not immediately return a request for confirmation.

"We were told it was indeed the SpaceX Rocket launched from Vandenberg Air Force Base," Phoenix Fire Department Capt. Rob McDade said in an email.